Washington --Toyota Motor Corp. officials insisted Tuesday in the strongest terms yet that there was no evidence that an electronic defect might be causing unintended acceleration of its vehicles despite compelling new data suggesting a link.

Claims data from insurer State Farm disclosed Tuesday suggests a strong connection between the introduction of electronic throttle control, also known as drive by wire, and events where drivers of Toyotas couldn't control their cars.

Claims relating to unintended acceleration in Toyota Camry sedans more than tripled in 2002 after the automaker introduced electronic throttle control in the model. Similar claims relating to the smaller Corolla nearly tripled in 2005, after it was equipped with electronic throttle control, according to State Farm, which warned the National Highway Traffic Safety Administration about the trends.

But Toyota officials on Tuesday maintained that the problem wasn't with the electronics, as they did in two hearings last week.

"Toyota has sold over 40 million vehicles with electronic throttle control and there's not a single case where it could identify the electronic throttle control as the cause of unintended acceleration," Executive Vice President Takeshi Uchiyamada, Toyota's chief engineer, told the Senate Commerce Committee.

In his opening remarks, Uchiyamada said that "as a result of our extensive testing, we do not believe sudden unintended acceleration because of a defect in our electronic throttle control system has ever happened."

Lawmakers expressed frustration as the third congressional hearing on Toyota's recalls failed to produce a clear explanation for potentially fatal cases of unintended acceleration in the Japanese automaker's vehicles.

Toyota's position that it's not an electronic problem "seems to be at odds with what many others believe to be the case," Sen. Byron Dorgan, D-N.D., said.

Toyota has recalled more than 6 million vehicles in the United States, and around 8.5 million worldwide, mainly to address acceleration-related issues. In some cases, Toyota is redesigning or fixing the gas pedals to keep them from sticking or getting entrapped by loose floor mats or other materials.

In response, Toyota is establishing a blue-ribbon panel of independent experts that will include former U.S. Transportation Secretary Rodney Slater to ensure that the automaker's new quality controls will be among the best in the industry. Toyota also is introducing an electronic failsafe measure, a brake override feature to make it easier for drivers to bring the car to a stop even if there's pressure on the accelerator.

Some senators, noting that unintended acceleration isn't limited to Toyota vehicles, said perhaps all cars and trucks should be equipped with a brake override feature.

"We must seriously consider mandating brake override," said Sen. John "Jay" Rockefeller, D-W.Va., the chairman of the Senate Committee on Commerce, Science and Transportation.

Rockefeller said legislative measures would be required, including a revisiting of the Tread Act passed after the last big safety scandal, when Ford Explorers with Firestone tires seemed to be at high risk of rollovers.

U.S. Transportation Secretary Ray LaHood said he was studying possible remedies. "We are looking at the possibility of recommending the brake override system to all manufacturers of automobiles," he said. "We think it's a good safety device."

Company culture criticized

In updated figures issued Tuesday, NHTSA said 52 deaths were connected to reports of sudden acceleration in Toyota vehicles since 2000.

The federal safety agency said 33 accidents involving 41 fatalities were reported in vehicles with electronic throttle control, introduced by Toyota in 2002 but now widespread among brands.

NHTSA Administrator David Strickland said that while Toyota's troubles have come into sharp focus, the large number of complaints reflects the company's growing U.S. market share.

"If you look at it on a per capita basis ... their actual comparison to the rest of the fleet was actually unremarkable," Strickland said. "They had the same percentage of sudden acceleration issues as other manufacturers. They just had more of them because they have more cars."

Although the tone of Tuesday's hearing was more cordial than the often contentious House hearings, senators criticized a company culture that seemed increasingly disconnected from safety concerns.

The committee released a document showing that Toyota's then-highest ranking U.S. executive Jim Press warned Japanese executives four years ago about the slipping quality and rising Toyota recalls in the U.S.

The presentation, dated Sept. 20, 2006, called for executives to "strengthen relationship with NHTSA and related organizations." And it urged Toyota officials in Japan to "support with timely, reasonable requests to investigations" and "consider image impact of technical responses" to safety concerns.

Rockefeller thanked the Toyota executives who had flown from Japan to testify, but expressed disappointment with the hearing.

"This has been useful, but not as useful as it should have been," he said.